Structures of Diamond-Like Carbon Films

The structures of diamond-like carbon (DLC) films, including a-C:H, a-C, ta-C:H and ta-C films have been investigated as a random covalent network with a dense film structure. The results show that sp² C in a-C:H and a-C films tends to form olefinic and aromatic groups while sp³ C in ta-C:H and ta-C films tends to form single or multiple sixfold groups. The hydrogen atoms in hydrogenated DLC films contribute to stabilizing the carbon skeletal networks. The film structures are well related to their properties such as optical gaps, density and hardness. The results also indicate that the high density and the extreme hardness of ta-C films are attributed to the forming of large sp³ C bonded sixfold groups.